DLL4 and colorectal cancer: Though conflicting results exist, an increase of JAG1, JAG2, DLL1, DLL3, DLL4 and NOTCH1-4 expressions are reported to be present in 75% of the colorectal cancer tissues and specifically, tumor cell-autonomous signaling can occur by a copy number gain of the NOTCH1 receptor, which can be found in 22% of colorectal cancers (Figure 1) [182,183].